Heretofore, it has been well known to provide a twin tie wing bracket having two distinctly separate tie wings with an archwire slot that is horizontally opening and buccolabially extending for use in the well known edgewise technique of orthodontic treatment. It has also been known to form such a bracket such that it has a buccolingual rhomboidal profile and also a buccolabial rhomboidal profile so that the archwire slot is squared with both profiles. Such a bracket is shown in U.S. Pat. No. 4,659,309.
It has also been well known to provide a single wing bracket having deep mesial and distal cutouts at the archwire slot for purposes of allowing unlimited tipping and uprighting movements in an edgewise bracket such as the bracket long ago developed by Alexander Sved, as disclosed in column 2 of U.S. Pat. No. 4,842,512.
Another form of a single tie wing edgewise bracket is shown in U.S. Design Pat. No. 290,040, which while having the appearance of a twin tie wing bracket and which does include cutouts at the mesial and distal sides of the bracket along the archwire slot, is in fact nothing more than a single wing bracket having four tie wing tips extending from the bracket slot that is positioned intermediate the tie wings, and thus cannot provide the advantages of a twin-wing bracket.
It has also been known to provide a twin tie wing bracket where the mesial and distal sides of the bracket are arcuately formed such as illustrated in U.S. Pat. No. 4,487,580 for the purpose of facilitating the gripping by an instrument. A bracket of this type is marketed under the trademark "Edgeway" by Ortho Organizers.
It has also been known to provide a single tie wing bracket having wings that are tapered to guide a tensioned resilient ligature into a seated position relative to the central portion, as illustrated in U.S. Pat. No. 3,626,593.
The prior known brackets and those above identified are limited in their operation and function.
It is well known that a twin tie wing bracket has many advantages over a single tie wing bracket. Twin tie wing brackets, sometimes called a twin bracket or a siamese bracket, by increasing mesiodistal archwire engagement, maintain better rotational control. Secondly, a true twin bracket allows effective single wing ligation on severely rotated teeth so that better leverage can be obtained. The true twin bracket further allows use of auxiliary components which are helpful with very short mesiodistal slot lengths. Such auxiliary components include torquing auxiliaries which can be used because they are disposed between the tie wings. Twin ligature ties may be used, one on each tie wing. Further, the mesiodistal slot length is increased over a single width bracket to yield more effective tip control.
Particularly, with respect to the bracket of U.S. Design Pat. No. 290,040, which is not a true twin bracket, it is not possible to allow placement of the single ligature tie on a severely rotated tooth, as it would cause the archwire to be in empty space at the edge of the bracket which would not provide any control between the archwire and the bracket. Further, this configuration would not allow the use of auxiliaries to be placed under the archwire and in between the bracket base and the lingual of the archwire.